The present invention relates to a battery unit mounting apparatus for an electric vehicle, a battery unit transfer apparatus used with the battery unit mounting device, and a method for mounting a battery unit.
Japanese Laid-Open Patent Publication No. 2010-173364 discloses a conventional battery unit transfer apparatus. The battery unit transfer apparatus includes a lift actuator for raising a polyhedron jig from below an electric vehicle, a battery fixing means for fixing a battery unit on the polyhedron jig, and an inclination adjusting means.
In the battery unit transfer apparatus, the battery fixing means fixes a battery unit on the polyhedron jig, and the lift actuator raises the polyhedron jig. The inclination adjusting means then rotates the polyhedron jig, thereby adjusting the inclination of the battery fixing means. Accordingly, the bottom of the body of the electric vehicle and the battery unit on the polyhedron jig become parallel with each other. Thus, even if the vehicle body is inclined relative to the horizontal plane because of occupants and cargo, the battery unit can be fixed to the vehicle body. Therefore, when mounting a battery unit to a vehicle body, the battery unit transfer apparatus is capable of easily mounting the battery unit to the vehicle body even if the electric vehicle is inclined.
The description of the above described conventional battery unit transfer apparatus does not clearly disclose a means for fixing the body of an electric vehicle and a battery unit to each other. However, it is assumed that fixing portions provided on the bottom of the vehicle body and portions-to-be-fixed of the battery unit are engaged with or disengaged from each other, so that the battery unit is mounted or removed. Since a battery unit is a heavy object, it is preferable that a vehicle body and a battery unit be engaged with each other at two or more, particularly, four or more locations, so that a battery unit is stably mounted on the vehicle body even while the electric vehicle is traveling. Hereinafter, a case will be discussed in which the above described battery unit transfer apparatus fixes a vehicle body and a battery unit to each other using fixing portions and portions-to-be-fixed, each being provided at four locations.
Due to manufacturing tolerances, the heights of fixing portions and portions-to-be-fixed vary. Such varied heights cause problems different from an inclination of a vehicle body. Therefore, even if the above described battery unit transfer apparatus adjust the inclination of a battery unit to match with the inclination of a vehicle body, the height variations are not resolved.